Monday, September 13, 2010

Samsung LN-S4041D LNS4041D shuts down intermittently

Well I'm back from Europe and overloaded with work!

This post is for a trivial problem with the BN44-00134A power supply used in some Samsung LCD TVs.

Just yesterday came across a LN-S4041D TV unit. It was brought in for service with complains for intermittent shutdowns after working for a while.

Sounds familiar - many TVs would do that, very often due to puffed capacitors in their power supply boards.
(of course it is not always the case; remember, nothing is ever certain, so the next time you call a service technician please spare their day and tell them the problem you see and not what you think is causing it!)

So anyway, after taking the back off and looking at the power board this is what I saw:


An even closer look at the upper right corner revealed the following:

Did you notice the two puffed caps? They are a little harder to see on the image - I am an electronics and software engineer, after all, not a photographer - but if you know they are there you will see them even on this image.

Puffed caps like that are usually connected in parallel and usually have the same value.

In this case they were both 1000 uF / 10V .

When replacing puffed caps it is usually best to use the same value for their capacity (1000 uF in this case) and always safer to use same or, better yet, higher value for their rated voltage.

Another important property of the electrolytic capacitors is the upper temperature range they can work on. On most boards these days this is 105 degrees Celsius and I recommend using the same or higher value.

Replacing those two with a pair of 1000 uF / 16V / 105 degrees fixes the set and will keep it running for a long long time.

Maybe happily ever after.

3 comments:

Mike said...

until something decides to go in the digital board. samsungs are notorious for that.

Vasco said...

thanks very much, just replaced the capacitors, the TV has now begun to function properly.
You're a great!
model TV SAMSUNG LE40M86BD
VascoR

dave said...

Worked like a champ for me-thanks!

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